Previously it was only working for the single layer case. For multipart
we write the colorspace in each part. For single part we write the first
non-data colorspace, and hope data passes will be identified based on channel
name like Blender does (e.g. XYZ instead of RGB).
Reading is unchanged and still the same as before, in that it only reads the
colorspace from the first part. There is only one color space per image
datablock, so we can not store anything more currently. In practice it
would be unusual for all passes in a file not to either have the same
colorspace or be data.
All the compositor file output test images were updated to include the
metadata, so that the test will check if the metadata is there.
Ref #144911
Pull Request: https://projects.blender.org/blender/blender/pulls/146809
e91c8300a6